Oxygen enhanced combustion in industrial processes

a technology of industrial processes and oxygen, applied in the direction of steam generation using hot heat carriers, machines/engines, lighting and heating apparatus, etc., can solve the problems of reducing the net demand of electricity of the oxygen supply system, less efficient steam power generation systems, etc., to reduce equipment costs, less efficient, and flexible operation

Inactive Publication Date: 2009-12-17
PRAXAIR TECH INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0010]Also, the invention seeks to integrate in an efficient manner the utilization of the power generated with the oxygen supply system, or any demand of electrical power within the industrial process considered. The power output of the alternative Rankine cycle could be in the form of electricity, and the alternative turbine of the alternative Rankine cycle can be directly coupled to one of the power consuming devices through a shaft or through a motor/generator assembly for reducing equipment cost associated with generating electricity and distributing it to different devices. Having a motor/generator assembly will provide flexibility in operation.
[0011]Use of oxygen enhanced combustion increases the availability of low-grade heat sources, which could become valuable opportunities for power generation. However, steam power generating systems are less efficient when heat source is available at temperatures lower than 400° C., due to lack of economic viability caused by poor achievable efficiency typical to steam processes at such low temperature. Generation of electrical energy by alternative Rankine cycles (includi

Problems solved by technology

However, steam power generating systems are less efficient when heat source is available at temperatures lower than 400° C., due to lack of economic viability caused by poor achievable efficiency typical to

Method used

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  • Oxygen enhanced combustion in industrial processes
  • Oxygen enhanced combustion in industrial processes
  • Oxygen enhanced combustion in industrial processes

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0038]Benchmark: An optimized air fueled cement plant has the following throughput and fuel consumption:

Plant Capacity:4000tpdFuel Consumption:131.7MWOxygen consumption:0.0kg / h

[0039]The heat sources from kiln and clinker cooler are given in Table 1, if no heat is recovered from these streams, the total exhausted heat amounts to 23.5% of the fuel consumed (calorific input).

TABLE 1Air fuel combustion without heat recoveryKilnClinker CoolerStreamExhaustExhaustFlow rate, kg / h274 000172 400Temperature ° C.332169Composition, % vol.N258.079.0O22.021.0CO234.20.0H2O5.80.0Heat Flow*, MW24.46.6Exhausted heat as %18.535.0Fuel Calorific Input*calculated for a temperature discharged of 35° C.

[0040]Moreover, low temperature of the hot air exiting the clinker cooler of 169° C. makes heat recovery using alternative Rankine cycle less feasible. Only the heat from flue gases is recoverable. Table 2 shows the amount of recoverable heat from each stream, the power generated considering an overall effici...

example 2

Partial Oxygen Enhanced Combustion

[0041]An increase by 25% in cement plant throughput can be achieved by increasing the fuel input and at the same time using about 47.5% of the oxygen required for combustion as pure oxygen, stream 104 as shown in FIG. 4.

Plant Capacity:5000tpdFuel Consumption, 101:191.7MWInput Oxygen, 104:28,460kg / h

[0042]The heat streams 106, 201 generated in this case are given in Table 3.

TABLE 3Oxygen enhanced combustion without heat recoveryExhaust kilnExhaust ClinkerStream(201)Cooler (106)Flow rate, kg / h287,000317,300Temperature ° C.332403Composition, % vol.N245.379.0O22.021.0CO244.70.0H2O8.00.0Heat Flow*, MW24.741.8Exhausted heat as %12.921.8Fuel Calorific Input*calculated for a temperature discharged of 35° C.

[0043]Table 4 shows the amount of recoverable heat from each stream, the power generated considering an overall efficiency of 18%, and recalculates the exhausted heat related to fuel consumption.

TABLE 4Oxygen enhanced combustion with heat recoveryExhaust k...

example 3

100% Oxygen Enhanced Combustion with Flue Gas Recirculation

[0044](a): No heat recovery through power generation.

[0045]A similar increase in throughput, by 25%, can be obtained switching to 100% oxygen enhanced combustion, and partial recirculation of the flue gases, to account for oxygen dilution as shown in FIG. 6, where no heat recovery is utilized.

Plant Capacity:5000tpdFuel Consumption, 101:184.7MWInput Oxygen, 104:60,000kg / h

[0046]The heat streams 106 and 201, 202 and 203, generated in this case are given in Table 5.

TABLE 5Complete oxyfuel conversion without heat recoveryExhaustExhaustClinkerkilnRecirculatedVentedCoolerStream(201)(202)(203)(106)Flow rate, kg / h331,600126,100205,500275,900Temperature ° C.332523Composition, % vol.N23.779.0O22.021.0CO281.60.0H2O12.80.0Heat Flow*, MW36.3—22.539.8Exhausted heat as %——1221.5Fuel Calorific Input*calculated for a temperature discharged of 35° C.

[0047](b): Heat recovery through power generation.

[0048]Table 6 summarizes the flow rate, tempe...

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Abstract

The present invention relates to a system for carrying out oxygen-enhanced combustion in an industrial process wherein the industrial process, an oxygen supply system or a source of oxygen, a heat recovery network, and an alternative Rankine cycle system based on a working fluid other than steam are integrated to achieve improved throughput and efficiency, and a method for oxygen-enhanced combustion in an industrial process using said system. Examples of industrial processes include cement production, steel reheat applications, glass production, aluminum and copper melting, as well as any industrial process that uses process heater, furnaces where combustion is carried out using an oxidant stream with oxygen content higher’ than that in ambient air and up to 100%.

Description

RELATED APPLICATION[0001]This application claims the priority to U.S. Provisional Application No. 60 / 833,258, filed on Jul. 25, 2006, the entire contents of which are incorporated by reference herein.TECHNICAL FIELD[0002]The present invention generally relates to the field of cogeneration of power and heat, and particularly to recover heat lost to ambient air using oxygen enhanced combustion.BACKGROUND OF INVENTION[0003]Oxygen enhanced combustion is utilized in industrialized furnace applications to increase throughput and has additional advantages such as lower emissions, improved flame stability and heat transfer. Although increased thermal efficiency is claimed for processes that use oxy-fueled combustion, making use of the unavoidably generated waste heat remains a challenge. Unlike air-fired processes, where the excess thermal energies from the flue gases are used to preheat the air for combustion, in oxygen enhanced combustion, the hazards of handling hot oxygen-enriched strea...

Claims

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Application Information

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IPC IPC(8): F23L7/00F25J3/04F01K25/08
CPCF01K13/00Y02E20/344F22B1/16F23C9/00F23L7/007F23L2900/07005F25J3/04521F25J3/04527F25J3/04533F25J3/04551F25J3/04557F25J3/04593F25J2230/22F25J2240/70F01K25/10Y02E20/34
Inventor BONAQUIST, DANTE PATRICKSHAH, MINISH MAHENDRACHAKRAVARTHY, VIJAYARAGHAVAN SRINIVASANZANFIR, MONICADRNEVICH, RAYMOND FRANCISLAUX, STEFAN
Owner PRAXAIR TECH INC
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